Question

I have the following class:

template <typename T>
class Fixed2DContainer {

    T* ptr;

public:
    const int total_cols;
    const int total_rows;

    Fixed2DContainer(int cols, int rows);
    T& operator()(int col_n, int row_n);
    ~Fixed2DContainer();

private : //disallow copy
    Fixed2DContainer& operator=(const Fixed2DContainer&);
    Fixed2DContainer operator()(const Fixed2DContainer&);
};

Now I’d like to specialize this template for some class so that the only change is that I can have an another constructor.
Basically I want to be able to do:

Fixed2DContainer<Image>("filename.jpg");

is there an elegant way to do this? I am fairly new to template so i have no idea of the difficulty

Answer 1

Here’s a quick example of what I meant in my earlier comment …

template <typename T>
class Fixed2DContainerBase {

  T* ptr;

public:
  const int total_cols;
  const int total_rows;

  Fixed2DContainerBase(int cols, int rows);
  T& operator()(int col_n, int row_n);
  ~Fixed2DContainerBase();

private : //disallow copy
  Fixed2DContainerBase& operator=(const Fixed2DContainerBase&);
  Fixed2DContainerBase(const Fixed2DContainerBase&);
};

// primary template
template <typename T>
class Fixed2DContainer : public Fixed2DContainerBase<T> {

  Fixed2DContainer(int cols, int rows);
  ~Fixed2DContainer();
};

// explicit specialization
template <>
class Fixed2DContainer<Image> : public Fixed2DContainerBase<Image> {

  Fixed2DContainer(int cols, int rows);
  Fixed2DContainer(const std::string&);
  ~Fixed2DContainer();
};

N.B. because the base class is non-copyable the derived classes will be too. It may not be necessary to define a destructor in the derived classes if all the cleanup can be done by the base destructor.